Recently, there has been a standard called a DVI in which video data are transmitted to a display device as digital data, when a video-signal source such as a television tuner, a video reproducing device, and a main unit of a personal computer, and an image display device such as a monitor receiving unit are connected.
Though the details of the DVI standard will be described later in an embodiment, the standard will be briefly described as follows. Video data are transmitted to a display device as data in which each of primary color signals R, G, B are digitalized in pixels, thereby high-quality picture being transmitted and displayed. Moreover, since the video data are pixel-unit data, a display driver on a display device side may be directly driven by the received video data to enable displaying and so on by a comparatively simple configuration for the processing.
However, basically only video data are transmitted through a cable defined by the DVI standard, and it is required to connect a tuner and so on to an audio output device using an audio cable different from the cable defined by the DVI standard, considering a case where audio data are simultaneously transmitted with video data. Therefore, there has been a problem that a connection configuration becomes complex when a plurality of cables are connected as described above.
Specifically, considering a system configuration in which only video data are transmitted, as shown in FIG. 1, for example, the video data encoded according to the DVI standard may be transmitted from a video-signal source 1 to a display device 3 by connecting them using a cable 2 of the DVI standard. On the other hand, as shown in FIG. 2, for example, when video data and audio data are transmitted from a video/audio signal source 4 to a display device 6 including a speaker, it is required that the video data are transmitted through the cable 2 according to the DVI standard, and, furthermore, the audio data are transmitted through an audio signal cable 5 different from the cable 2. According to a connection shown in FIG. 2, the image output from the video/audio signal source 4 may be displayed on the display device 6, and sounds may be output from speakers 6L, 6R installed in the display device 6.
However, when it is configured as shown in FIG. 2 in which different cables for the video data and the audio data are respectively used to connect, there has been a problem that a connection configuration becomes more complex. The number of cables to connect devices is preferably small.
A data transmission technology using a bus line according to an IEEE (The Institute of Electrical and Electronics Engineers) 1394 standard, for example, may be applied to a technology for transmitting video data and audio data using one cable after multiplexing both the data. However, highly complex data processing is required for data transmission using the bus line according to the above IEEE1394 standard or the like, and therefore, extremely large-scale circuit configuration is required to perform encoding processing for transmission on a sending side, and to perform decoding processing of the data received through the bus line on a receiving side; and the cost may increase. Moreover, in the IEEE1394 standard or the like, video data and audio data are compressed and encoded to multiplex them in view of a transmission rate and so on. Therefore, there has been a disadvantage that the quality of picture may be degraded compared with that in the above described DVI standard in which the video data are digitalized in pixels to be transmitted.
Moreover, when digitalized audio data are transmitted, error-correction processing which is different from the processing necessary for transmitting video data is required. As a result, there has been a problem that a configuration for processing audio data becomes complex both on the sending and receiving sides when particular processing is performed for the error correction.